Method for frozen ground consolidation in thawed zone

FIELD: building, particularly to consolidate frozen ground in thawed zone under building foundation.

SUBSTANCE: method involves driving injector in ground; injecting consolidation penetrative mix under pressure, which provides ground structure in weakened ground zones and ground compaction along compacted zone perimeter; following injector driving to create compacted zones adjacent above zones. The consolidation penetrative mix is cooled salt solution comprising filler of material having lesser heat conductivity in comparison with ground to be compacted.

EFFECT: extended field of method application, increased reliability and efficiency.

5 cl, 1 ex, 1 dwg

 

The present invention relates to the construction, in particular to strengthen the frozen ground in the area of thawing under the foundations of buildings and structures.

Known methods of strengthening frozen soil using different cooling devices, such as freezing columns with different location (Artificial base. M: State. publishing house of literature on construction, architecture and building materials, 1961 / the Academy of construction and architecture of the USSR. Institute of foundations and underground structures. Sat. No. 45, p.71-75), chillers (ibid, p.45), tubular cooling air systems (Foundations of buildings on frozen soils of Yakutia. M.: Nauka, 1968, s).

A disadvantage of known methods is the need to maintain the temperature in the Foundation soil and the high cost of maintaining the set temperature mode.

Closest to the present invention is a method of soil compaction, including immersion in the soil injector, feed solution under pressure, the measurement and recording of pressure solution, the formation area of the compacted soil and the subsequent submersion of the injector with the formation of adjacent zones of compacted soil, and compaction of dispersed soil produced by injection of sealing and penetrating solution to ensure the destruction of art is ucture soil in areas of weakening, preliminary soil compaction on the contour of the seal area (patent RF №2119009, publ. 20.09.98, priority 27.01.97).

The disadvantage of this method is the inability to strengthen this method permafrost soil due to possible further thawing through the heat-conducting layer formed of the seal area. The presence in the area of the sealing water in the permafrost often leads to additional thawing of the soil and increase its sediment. In the contact area with permafrost formed ice layer, which is in the process of operation in the temperature fluctuations may again turn into water. In addition, the presence of water in the zone of compaction significantly slows down the process of filing sealing and penetrating solution and, therefore, reduces the efficiency of this method.

The technical problem to be solved in the present invention, is to expand the field of application of the method to strengthen the frozen ground in the area of thawing while increasing its reliability and efficiency.

The problem is solved in that way strengthen the frozen ground, including immersion in the soil injector, the flow of sealing and penetrating solution under pressure, ensuring the destruction of the structure of the soil in areas of weakening with the formation of the compacted zone, grunto the contour of the seal area and the subsequent submersion of the injector for the formation adjacent areas of compaction, as sealing and penetrating solution using the solution with filler, while in use as a filler material with a thermal conductivity less than thermal conductivity of the strengthening of the soil, such as expanded clay, perlite, Styrofoam, etc. This creates in strengthening the insulating area of the screen, contributing to the lowering of its temperature, preventing further thawing and reducing the likelihood of precipitation of the soil.

It is advisable before applying the sealer and penetrating solution to enter into the soil filter for water outflow which would increase the rate of outflow of water from the seal area due to the large pressure created by the injector in the area of the seal. This improves the reliability of strengthening of frozen soil in the area thawing due to dehydration strengthen areas with increasing feed speed sealing and penetrating solution.

Suitable as sealing and penetrating solution is to use chilled saline solution with filler. This eliminates the additional thawing of the soil and associated subsidence of the Foundation by means of lowering the temperature of the seal area and accelerate the freezing of the soil.

The present invention is illustrated in the drawing, which presents the scheme of strengthening of the frozen ground.

DL is the implementation of the proposed method is used injector 1 for supplying sealing and penetrating solution and filter 2 for reception of the water.

The proposed method is as follows. The injector 1 is dipped in the soil under the pile Foundation 3 zone 4 thawing during operation. Injected into the soil filter 2 for the outflow of water and served in a zone of low thawed soil 5 salt cooled solution of 6 with filler, thermal conductivity of which is lower than the ground. A solution of 6 serves under pressure, ensuring the destruction of the structure of the soil in areas of weakening with the formation of a zone of compacted soil around the edge of the zone 7 seals. Nizkoteploprovodnye materials do not absorb water unlike, for example, cementitious materials, and lobophyllia saturated frozen soils may not provide a fast outflow of water from the seal area. Filter 2 provides a rapid outflow of water from the seal area due to the large pressure in the seal area, thereby improving the insulating properties of the seal area and increase the feed rate of the solution 6. For the formation of adjacent zones seals produce subsequent immersion of the injector 2 to the education zone 7 of the compacted soil, almost adjacent to the natural boundary of 8 frozen soil. Area 7 of the compacted soil forms a heat insulating screen, preventing further thawing permafrost soil, excluding the possibility of additional sediment GRU is the same. Experimental studies have shown that after completion of the border 9 permafrost soil is moved to the surface of the land is in zone 7 of the compacted soil by lowering the temperature of a zone of thawing. The new frontier 9 permafrost (the border of negative temperatures) is determined by the maximum possible temperature difference on the surface of the earth and layers of permafrost, the thickness of the insulating layer, the coefficient of thermal conductivity of soil and heat insulating material.

Thus, the proposed method can effectively and reliably to strengthen and protect further from temperature permafrost soils under the foundations of buildings and structures, to increase their load carrying capacity.

A specific example of the proposed method of strengthening the frozen ground in the area of thawing.

The base of the building three-storey dwelling house is permanently frozen ground, lying at a depth of 5.5 m from the natural boundary of permafrost soil. To transfer the load from the foundations on permafrost soil used frozen it piles section 0,30×0.30 m and a length of 8 m Thawed soil located directly under the sole Foundation, presents megaplatinum loam, permanently frozen soil - plastic loam layered cryogenic texture with thick ice up to Δ l=70 mm, the Density of the frozen ground in a dry condition pdf=1.12 g/cm3. When thawing the relative compression is is 0.135. At the time of sealing the border of the permafrost soil after thawing during operation fell by 1.7 m, which led to a large and uneven precipitation of the building Foundation. Upon further advancement of the front of thawing the building could collapse. In the soil under the pile Foundation was introduced injector; a filter for water outflow introduced in the middle of the pile foundations. Through the injector in a layer of thawed soil is introduced under pressure chilled saline solution filled with expanded clay sand with a density of p0=0,68 g/cm3and thermal conductivity λ=0.27 W/MK, which is 6 times less than thermal conductivity of conventional cement sealing and penetrating solution and 5.8 times less thermal conductivity of natural soils. Only in the area of thawing entered 0,32 m3solution 1 m3the compacted zone. As a result of natural soil in the area of the seal has acquired the density of dry soil ρand=1,65 g/cm3. The seal formed teploizoljatsionnye screen thickness on average of 0.55 m, which helped to stop further thawing of the base, lower the temperature of the soil in the zone of the tip of the piles and to reduce the relative compression to turn the key to zero, discontinuing thus the draught of pile Foundation. After a time of approximately three days from the time the work was investigated fundamental region by sampling the deep layers. It was established that the boundary of the permafrost soil after stabilization temperatures moved into the area of the seal. Use one filter for receiving water allowed to speed up the process of compaction from 5 to 2 days.

Thus, the strengthening of frozen soil in the area thawing carried out by supplying under pressure to the weakened area of the soil solution with a filler material which has good thermal insulation properties, in contrast to known methods strengthen the soil with the use of sand-cement mixtures, allows to displace the boundary of negative temperatures in the area thawing, securely to strengthen and protect further from temperature fluctuations permafrost soil, the use of chilled saline solution eliminates the additional thawing of the soil, and the application of the filter to drain water from the zone of compaction and dehydration of the solution when the injection increases the feed rate of solution increases the reliability and efficiency of the proposed method.

1. A way to strengthen frozen ground in the area of thawing, R is the overall immersion into the soil injector, supply sealing and penetrating solution under pressure, ensuring the destruction of the structure of the soil in areas of weakening with the formation of a zone of compacted soil around the edge of the seal area, and the subsequent submersion of the injector for the formation adjacent areas of the seal, characterized in that the sealing and penetrating solution using chilled saline solution with a filler material, thermal conductivity of which is lower than thermal conductivity of strengthening the soil.

2. The method according to claim 1, characterized in that the filler used ceramsite sand.

3. The method according to claim 1, characterized in that the filler used granulated foam.

4. The method according to claim 1, characterized in that the filler used perlite.

5. The method according to any one of claims 1 to 4, characterized in that before applying the sealer and the penetrating solution is injected into the soil filter to drain water from the seal area.



 

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EFFECT: increased quality of base and foundation member production.

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